1. Field of the Invention
The present invention relates to an operation lever device, and more particularly to an operation lever device which can output an oil pressure signal by twisting an operation lever.
2. Description of the Related Art
The bulldozer is provided with a blade. The blade is operated to perform xe2x80x9cblade up, down, and floatxe2x80x9d, xe2x80x9cright tilt and left tiltxe2x80x9d, and xe2x80x9cright angle and left anglexe2x80x9d. To make such operations, the bulldozer is provided with hydraulic cylinders and flow rate control valves for respective operations. Specifically, the bulldozer is provided with a blade up-and-down flow-rate control valve, a tilting flow-rate control valve and an angle control valve. Those three flow rate control valves are driven by operating the hydraulic operation lever. More specifically, when the hydraulic operation lever is operated, a pilot pressure corresponding to an operated amount is applied to respective pilot ports of the flow rate control valves. And, a pressure oil with a flow rate corresponding to the pilot pressure applied to each pilot port is supplied to the each hydraulic cylinder. Thus, the blade is operated.
When it is necessary to operate three flow rate control valves, namely operation objects for three axes by at least two operation levers, the operations are troublesome, placing a burden on the operator.
Therefore, an operation lever device which can operate the operation objects for three axes by a single operation lever has been proposed heretofore.
Japanese Patent Publication No. 3-44326 describes an invention of an electric operation lever device which can operate the operation objects for three axes by freely operating an electric operation lever in three directions of back and forth, right and left, and twisting.
But, the electric operation lever needs a sensor such as a potentiometer in order to detect an operated amount. And, a controller and an electromagnetic proportion valve are also needed to convert an electric signal output from the electric operation lever into an oil pressure signal. Accordingly, it has disadvantages that the number of components is increased and the structure becomes complex.
Japanese Patent Application Laid-Open Publication No. 7-117705 also describes an invention of an operation lever device which can operate operation objects for three axes by freely operating an operation lever in three directions of back and forth, right and left, and twisting.
Such an operation lever device has a structure having the operation lever connected to a spool of the flow rate control valves by a link mechanism. Operation of the operation lever directly pushes or pulls the spool of the flow rate control valve through the link mechanism.
But, the above link structure for the three axes is complex. It has disadvantages that its components require high accuracy, and the assembly and adjustment of the operation lever device require a great deal of time. It also has drawbacks that the force to operate the operation lever has to be high and the operator becomes tired easily because the spool of the flow rate control valve is directly pushed or pulled through the link mechanism. Besides, the operation lever and the flow rate control lever are mutually disposed uniquely and must be accurate because the operation lever is connected to the spool of the flow rate control valve through the link mechanism. Thus, there is another disadvantage that the layout of the respective equipment is restricted.
Meanwhile, an invention related to a biaxial hydraulic operation lever device which can output an oil pressure signal when the operation lever is operated in a back and forth direction and a right and left direction is known well. But, an invention directed to a hydraulic operation lever device which can output an oil pressure signal by operating the operation lever in a twisting direction has not be achieved yet.
It is a first object of a first aspect of the present invention to make it possible to output an oil pressure signal by operating the operation lever in the twisting direction, to make a structure simple, to facilitate its assembly and adjustment, to lower its operation force, and to eliminate the restriction of its layout.
The operation lever device used for construction machines such as a bulldozer is sometimes provided with a mechanism for keeping the operation lever in a tilted state. The mechanism for keeping the operation lever in the tilted state is called a detent mechanism.
But, it was found that the disposition of the detent mechanism for the operation lever device which operates the operation lever in three directions of back and forth, right and left, and twisting has the following drawbacks.
Specifically, when shaft section 8c of the operation lever of FIG. 2 is tilted, the bottom surface of disk plate 9 comes into contact with top end (stopper) 12a of plate 12. At the time, when the detent mechanism is operating, the shaft section 8c of the operation lever is fixed in a tilted position.
When the shaft section 8c of the operation lever in the aforesaid state is twisted, frictional force is produced between the bottom surface of the disk plate 9 and the top end 12a of the plate 12. Therefore, even if the hand is moved off the operation lever after the shaft section 8c of the operation lever is twisted, the shaft section 8c of the operation lever does not return smoothly to the original neutral position because of the frictional force.
It is a second object of a second aspect of the invention to enable the operation lever return to the original neutral position smoothly when the hand is moved off the operation lever after it is twisted.
Therefore, in order to achieve the first object, the first aspect of the invention is an operation lever device which moves pistons (5, 6) according to an operation of operation lever (8), outputs an oil pressure signal according to the movement of the pistons (5, 6) and operates operation object (33) according to the oil pressure signal, and is comprised of twisting means (13, 14, 15) for twisting the operation lever (8) about lever axis (8a), and conversion means (18, 19) for converting the motion to twist the operation lever (8) about the lever axis (8a) into motion to move the pistons (5, 6).
The first aspect of the invention will be described specifically with reference to FIG. 2.
According to the first aspect of the invention, when the operation lever 8 is twisted about the lever axis 8a, the shaft 13 supported by the bearings 14, 15 is twisted. The twist of the shaft 13 is converted into the movement in a direction that the piston 5 is moved by the first lever 18 and the second lever 19, and the piston 5 is moved. When the piston 5 is moved, the oil pressure signal is output from discharge port 25.
According to the first aspect of the invention, the operation lever device 10 may be provided with a mechanism for twisting the operation lever 8 and a mechanism for converting the twist into motion to move the piston 5. Therefore, it is different from a conventional electric operation lever device and has a simple structure without requiring a sensor, a controller and the like.
Besides, it is not a structure to directly push or pull the spool of the flow rate control valve by a link mechanism but follows a structure to output the oil pressure signal according to the movement of the pistons in the same way as the conventional hydraulic operation lever device. Therefore, the operation lever device can be assembled and adjusted easily without necessitating lots of time. Because the pistons are moved by operating the operation lever in the same way as the conventional hydraulic operation lever device, the operation lever is operated by the same small force as before, and an operator does not get tired. Besides, it is not a structure having the operation lever and the spool of the flow rate control valve connected by a link mechanism but a structure following the structure which outputs the oil pressure signal according to the movement of the pistons in the same way as the conventional hydraulic operation lever device. Therefore, it is not necessary to closely dispose the operation lever and the flow rate control valve and does not restrict the layout of respective equipment.
As described above, the oil pressure signal can be output by operating the operation lever in the twisting direction according to the first aspect of the invention, so that there are effects that the structure is simple, its assembly and adjustment are easy, the operation force can be reduced, and the respective equipment can be laid out freely.
A second aspect of the invention is an operation lever device which moves pistons (1, 2, 3, 4) according to a tilted direction and a tilted amount of operation lever (8), outputs an oil pressure signal according to the movement of the pistons (1, 2, 3, 4) and operates operation objects corresponding to first and second shafts (31, 32) according to the oil pressure signal, and is comprised of pistons (5, 6) for third shaft (33) disposed in correspondence with an operation object corresponding to the third shaft (33), twisting means (13, 14, 15) for twisting the operation lever (8) about lever axis 8a, and conversion means (18, 19) for converting the movement to twist the operation lever (8) about the lever axis (8a) into motion to move the third-shaft pistons (5, 6).
The second aspect of the invention will be described specifically with reference to FIG. 2.
According to the second aspect of the invention, when the operation lever 8 is tilted, the pistons 1, 2, 3, 4 are moved, the oil pressure signal is output according to the movements of the pistons 1, 2, 3, 4, and the control valves 31, 32 are operated according to the oil pressure signal.
When the operation lever 8 is twisted about the lever axis 8a, the shaft 13 supported by bearings 14, 15 is twisted. The twist of the shaft 13 is converted into the movement in a direction to move the pistons 5, 6 by the first lever 18 and the second lever 19, and the pistons 5, 6 are moved. When the pistons 5, 6 are moved, the oil pressure signal is output from discharge ports 25, 26. The control valve 33 is operated according to the oil pressure signal.
According to the second aspect of the invention, the same effects as those by the first aspect of the invention can be obtained. According to the second aspect of the invention, there is provided an effect that operation objects (control valves 31, 32, 33) of three axes can be operated by a single hydraulic operation lever 8.
A third aspect of the invention is an operation lever device which is provided with tilting fulcrum (11) for supporting the root of operation lever (8) and tilting the operation lever (8), moves pistons (1, 2) according to the tilting operation of the operation lever (8), outputs an oil pressure signal according to the movement of the pistons (1, 2), and operates operation object (31) according to the oil pressure signal, and is provided with twisting means (13, 14, 15) for twisting the operation lever (8) about the lever axis (8a), and conversion means (18, 19) for converting the movement to twist the operation lever (8) about the lever axis (8a) into movement to move pistons (5, 6), wherein the twisting means (13, 14, 15) and the conversion means (18, 19) are disposed on the other side of the operation lever (8) with the tilting fulcrum (11) therebetween.
The third aspect of the invention will be described specifically with reference to FIG. 2.
According to the third aspect of the invention, twisting mechanism for twisting the operation lever 8 and conversion mechanisms (the shaft 13, the bearings 14, 15, the first lever 18, the second lever 19, etc.) for converting to the movement for moving the pistons 5, 6 are disposed below the universal joint 11 which supports the root of the operation lever 8 and tilts the operation lever 8.
According to the third aspect of the invention, even when the operation lever 8 is tilted, its movement does not give an effect on the movements of the mechanisms below the universal joint 11. Therefore, the twisting mechanism and the conversion mechanism can be configured independent of the tilting of the operation lever 8, and the structure can be made simple.
In order to achieve the second object, a fourth aspect of the invention is an operation lever device which is provided with the disk plate (9) to which the root of the operation lever (8) is attached and the tilting fulcrum (11) which tiltably supports the disk plate (9), moves the pistons (1, 2) via the disk plate (9) according to the tilting operation of the operation lever (8), and outputs a signal according to the movements of the pistons (1, 2) to operate the operation object (31) according to the signal, wherein:
the disk plate (9) is separated into a first disk plate (9a) to which the root of the operation lever (8) is attached and a second disk plate (9b) which is tiltably supported by a tilting fulcrum (11);
twisting means (13, 50, 51) are disposed to twist the first disk plate (9a) about the lever axis (8a) of the operation lever (8) independent of the second disk plate (9b); and
a signal corresponding to the twisted position of the first disk plate (9a) about the lever axis (8a) is output to operate the operation object (33) according to the signal.
The fourth aspect of the invention will be described with reference to FIG. 20.
According to the fourth aspect of the invention, the disk plate 9 is separated into the first disk plate 9a to which the root of the operation lever 8 is attached and a second disk plate 9b which is tiltably supported by a tilting fulcrum 11. And, the first disk plate 9a becomes independent from the second disk plate 9b and twists about the lever axis 8a of the operation lever 8.
According to the fourth aspect of the invention, when the operation lever 8 is twisted, only the first disk plate 9a is twisted about the lever axis 8a independent of the second disk plate 9b, so that the twist about the lever axis 8a of the operation lever 8 is not affected by the frictional force produced between the second disk plate 9b and the top end 12a of the plate 12.
Therefore, when the hand is moved off the operation lever 8 after twisting it, the operation lever 8 returns to the original neutral position smoothly.
A fifth aspect of the invention is an operation lever device which outputs a signal according to the operation of the operation lever (8) to operate the operation object (33) according to the signal, which comprises:
the twisting means (13, 14, 15) for twisting the operation lever (8) about the lever axis (8a) from its neutral twisting position to a predetermined twisting position, and
elastic member (52) for returning the operation lever (8) to its neutral twisting position when the operation lever (8) is twisted about the lever axis (8a).
The fifth aspect of the invention will be described with reference to FIG. 20.
According to the fifth aspect of the invention, when the operation lever 8 is twisted about the lever axis 8a, the operation lever 8 is returned to its neutral twisting position by means of the elasticity of the elastic member 52.
Therefore, when the hand is moved off the operation lever 8 after it is twisted, the operation lever 8 is returned smoothly to its original neutral position.
A sixth aspect of the invention is an operation lever device which is provided with the disk plate (9) to which the root of the operation lever (8) is attached and the tilting fulcrum (11) which tiltably supports the disk plate (9), moves the pistons (1, 2) via the disk plate (9) according to the tilting operation of the operation lever (8), and outputs a signal according to the movements of the pistons (1, 2) to operate the operation object (31) according to the signal, wherein:
the disk plate (9) is separated into a first disk plate (9a) to which the root of the operation lever (8) is attached and a second disk plate (9b) which is tiltably supported by the tilting fulcrum (11);
twisting means (13, 50, 51) are disposed to twist the first disk plate (9a) about the lever axis (8a) of the operation lever (8) independent of the second disk plate (9b) from the neutral twisting position to a predetermined twisting position;
elastic member (52) is disposed to return the first disk plate (9a) to the neutral twisting position when the first disk plate (9a) is twisted about the lever axis (8a), and
a signal is output according to the twisting position of the first disk plate (9a) about the lever axis (8a) to operate the operation object (33) according to the signal.
A sixth aspect of the invention is a combination of the fourth aspect of the invention and the fifth aspect of the invention.
A seventh aspect of the invention is the operation lever device according to the fourth aspect of the invention or the sixth aspect of the invention, wherein the first disk plate (9a) is twistably supported by the second disk plate (9b) through a bearing (53).